Enum BuildError 

pub enum BuildError {
    MissingRequired {
        field: &'static str,
    },
    InvalidValue {
        field: &'static str,
        reason: String,
    },
    InvalidRange {
        field: &'static str,
        min: u64,
        max: u64,
    },
    ConflictingOptions {
        option_a: &'static str,
        option_b: &'static str,
    },
    InvalidProbability {
        field: &'static str,
        value: f64,
    },
    InvalidDuration {
        field: &'static str,
        reason: String,
    },
    DependencyMissing {
        feature: &'static str,
        dependency: &'static str,
    },
    Custom {
        message: String,
    },
}

Errors that can occur when building a configuration.

BuildError captures validation failures, constraint violations, and configuration errors that can occur during the build() call.

Error Categories

Category	Description	Example
MissingRequired	Required field not set	name field is None
InvalidValue	Value fails validation	threads = 0
InvalidRange	Range constraints violated	min > max
ConflictingOptions	Mutually exclusive options	sync and async both set
InvalidProbability	Probability not in [0.0, 1.0]	0.5..=1.5
InvalidDuration	Duration constraint violated	timeout = 0
DependencyMissing	Required dependency not configured	tls without certificates
Custom	Domain-specific validation errors	Application-specific rules

Usage

fn build(self) -> BuildResult<Config> {
    // Check required fields
    let name = self.name.ok_or_else(||
        BuildError::missing_required("name")
    )?;

    // Validate values
    if self.threads == 0 {
        return Err(BuildError::invalid_value("threads", "must be >= 1"));
    }

    // Check ranges
    if self.min_connections > self.max_connections {
        return Err(BuildError::invalid_range(
            "connections",
            self.min_connections,
            self.max_connections,
        ));
    }

    Ok(Config { name, threads: self.threads, ... })
}

Variants

MissingRequired

A required field was not set.

Example

BuildError::MissingRequired { field: "name" }

Fields

field: &'static str

The name of the missing field.

InvalidValue

A field value failed validation.

Example

BuildError::InvalidValue {
    field: "worker_threads",
    reason: "must be >= 1".to_string(),
}

Fields

field: &'static str

The field that failed validation.

reason: String

Why the value is invalid.

InvalidRange

A range constraint was violated (min > max).

Example

BuildError::InvalidRange {
    field: "connections",
    min: 100,
    max: 10,
}

Fields

field: &'static str

The field or field pair with the range issue.

min: u64

The minimum value provided.

max: u64

The maximum value provided.

ConflictingOptions

Two options that cannot both be enabled were set.

Example

BuildError::ConflictingOptions {
    option_a: "single_threaded",
    option_b: "work_stealing",
}

Fields

option_a: &'static str

The first conflicting option.

option_b: &'static str

The second conflicting option.

InvalidProbability

A probability value was not in [0.0, 1.0].

Example

BuildError::InvalidProbability {
    field: "cancel_probability",
    value: 1.5,
}

Fields

field: &'static str

The field with the invalid probability.

value: f64

The invalid probability value.

InvalidDuration

A duration value violated constraints.

Example

BuildError::InvalidDuration {
    field: "timeout",
    reason: "must be non-zero".to_string(),
}

Fields

field: &'static str

The field with the invalid duration.

reason: String

Why the duration is invalid.

DependencyMissing

A dependency required by the configuration is missing.

Example

BuildError::DependencyMissing {
    feature: "tls",
    dependency: "certificate",
}

Fields

feature: &'static str

The feature that has the missing dependency.

dependency: &'static str

The name of the missing dependency.

Custom

A custom validation error with arbitrary message.

Use this for domain-specific validation that doesn’t fit other variants.

Fields

message: String

The error message.

Implementations

impl BuildError

pub const fn missing_required(field: &'static str) -> Self

Creates a MissingRequired error.

pub fn invalid_value(field: &'static str, reason: impl Into<String>) -> Self

Creates an InvalidValue error.

pub const fn invalid_range(field: &'static str, min: u64, max: u64) -> Self

Creates an InvalidRange error.

pub const fn conflicting_options( option_a: &'static str, option_b: &'static str, ) -> Self

Creates a ConflictingOptions error.

pub const fn invalid_probability(field: &'static str, value: f64) -> Self

Creates an InvalidProbability error.

pub fn invalid_duration(field: &'static str, reason: impl Into<String>) -> Self

Creates an InvalidDuration error.

pub const fn dependency_missing( feature: &'static str, dependency: &'static str, ) -> Self

Creates a DependencyMissing error.

pub fn custom(message: impl Into<String>) -> Self

Creates a Custom error.

pub const fn field(&self) -> Option<&'static str>

Returns the field name associated with this error, if any.

pub const fn is_missing_required(&self) -> bool

Returns true if this is a missing required field error.

pub const fn is_invalid_value(&self) -> bool

Returns true if this is an invalid value error.

pub const fn is_conflicting_options(&self) -> bool

Returns true if this is a conflicting options error.

Trait Implementations

impl Clone for BuildError

fn clone(&self) -> BuildError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BuildError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for BuildError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for BuildError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for BuildError

fn eq(&self, other: &BuildError) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for BuildError